Wednesday, July 29, 2015

DEC axis unresponsive!!!

My nice, new MyT mount suddenly stopped slewing. First, I had a couple of "mount can't slew" warnings. I thought that I exceeded limits. But then the DEC axis completely stopped working. Rebooted the mount. Restarted TSX. Rebooted computer... Nothing

posted on bisque forum, but didn't get any good replies.

Checked all cables and connections ... Nothing.

Finally, contacted a friend who got me in touch with Daniel Bisque. We finally figured out that the DEC axis can't even initialize (the DEC led doesn't stop blinking at startup). Checked the driver, the cables again ... Nothing.

Tried everything with clutches off to make sure that nothing is stuck ... Nothing.

So, we decided to exchange the MTS 5000 board. Sent mine in...

August 30
... got a new one back. Installed ... Nothing.

Tried to read the DEC index - didn't work either.

The next guess was that it might be the cable itself.

Sep 14
Received a new cable. Installed ... Nothing.

Tried everything again (initializing, reading DEC index ...) ... Nothing

Oct 2
Next guess was that it was the motor / worm block. I received a new one.

Connected it (without installing it in the mount) to the board. Started. SUCCESS!!! Both RA and DEC initialized.

Next, I installed the new worm assembly and connected it. Still works.

Next, adjusted the Cam Stop - couldn't find exact value for MyT. Screwed the screw in until it hit the plate and then backed it off a little. Could still easily move the mount when disengaging the worm gear.

Next, set the Motor Index Angles.

Next, wanted to "excercise the mount" - did not work. Mount doesn't move and the RA and DEC lights blink and beep.

Maybe the mount needs to be better balanced. Attached the counterweight shaft - still the same result.

Tried to home the mount first - same result.

Tried to slew the mount with the handset - same result.

Next, I mounted the scope and the counterweights to get really good balance - same result.

Well, closer but no cigar. Mailed Bisque again ...

Wednesday, July 22, 2015

CCDAutopilot only takes subframes ! (for initial test frames - dooohhh!!!)

When I tried to take flats with CCDAutopilot at GSSP, it suddenly only took small subframes!!!

I restarted CCDAP, TSX, rebooted the computer, plugged the camera out and in ... nothing. It kept switching subframes on when it took flats. I ended up borrowing John's flat panel and used that for flats.

At home, I investigated more but couldn't figure out what was wrong. There was nothing suspicious in the log file. I also couldn't find any setting in CCDAP. I posted about this on the CCDWare forum. And John Smith (as usual) asked for a log file. That evening, I tried it again to get a log file, but was then distracted and kept CCDAP running.

... and suddenly realized that the flats that CCDAP took were full frame!!!

After more investigation, it turns out that CCDAP started to take the test frames (to check if the right brightness level is reached) as subframes and then takes that real flats as full frames. Probably to make the initial test frames faster to download. I'm sure that was in some release notes ...

Sunday, July 5, 2015

Paramount MyT - Day 10 - Further tweaks to PHD2, SGPro and the MyT driver & Rotating base plate!!!

Carried my scope out after our vacation. I set the scope in roughly the same place where I had it before our vacation, but could immediately see that the polar alignment would be completely off in Azimuth. Apparently, what happened when I carried the scope outside, I rotated the base plate (I noticed this earlier that it's not completely sticky). I asked on the Software Bisque forum about that.

Next, I needed to calibrate my model and redo my polar alignment. I connected the scope, homed it and then slewed it to Arcturus. I put the red dot finder on the scope, turned the base plate until Arcturus was close to center. Then I ran a model with 37 points. did an accurate polar alignment, ran another model and had my PA at 19.1 arcsec Azimuth and -67.3 arcsec Altitude. Pretty good.

As GSSP is in 10 days(!!) I decided to use the MyT mount without relying on T-Point slewing and tracking accuracy. I.e. I unchecked the "Inhibit Sync to protect TPoint model" setting in SGPro. This would allow SGPro to do proper center commands. Before doing that, I exported my current model to make sure that I still have it (not sure if adding syncs from SGPro would have any effect on the stored model).

I then calibrated PHD2 and wanted to do some manual tests. Noticed for the first time that PHD2 does not seem to notice when the MyT mount slews (I verified that the "Stop guiding when mount slews" setting is checked). So, I have to remember to manually stop it if I want to slew the mount.

First, I wanted to see how the mount is tracking without guiding:

The measured PA error of 1.21arcmin is consistent with the one from TPoint (19.1 arcsec Azimuth and -67.3 arcsec Altitude = 1.16arcmin). Good at least I don't have these inconsistencies between TPoint and PHD2 anymore. It's hard to see what the tracking accuracy is with the slope, but it seems to be below 1 arcsec...

Then the next surprise: suddenly, PHD2 corrected the DEC axis wrongly... Turns out, I need the "Reverse DEC output after meridian flip setting" in PHD2. With that, everything worked.

By now it was late again and I wanted to see how guiding would work. I setup a sequence on SGPro to image the core of NGC 7822. Here is the PHD2 guiding output:

There are the usual dithering spikes. In between, both RA and DEC are mostly below 1 arcsec - which is typical for seeing in our backyard. And the guide box shows that corrections were applied at >0.6 arcsec but maybe not aggressive enough and/or often enough. Need to work on calibrating PHD2 now.